A series of samples have been characterized by 3D image analysis (using X-Ray microtomography). The samples consist of blends of metallic particles: steel shot abrasives (“balls”), steel fibres and ... [more ▼]

A series of samples have been characterized by 3D image analysis (using X-Ray microtomography). The samples consist of blends of metallic particles: steel shot abrasives (“balls”), steel fibres and angular steel grit particles. The blends were systematically prepared in different proportions of the raw products. Various shape and size parameters were measured on the particles: equivalent volume diameter (dV), maximum inscribed sphere diameter (dIN), particle length (maximum Feret diameter), particle elongation (El), particle flatness (Fl) etc. The results are expressed as statistical shape and size parameters, expressed both as volume and number weighted distributions. The blends have been tested for compaction using a cylindrical container which experiences a series of 500 free falls over a height of 3mm. The compaction dynamics was monitored using a sensor that measures the evolution of the solid volume fraction as a function of the tap number. From the obtained compaction curve, the Hausner ratio and a flowability index were extracted. The same blends have also been analysed using a rotating drum at different rotation speeds to analyze the evolution of the flowing angle. As the system is based on the analysis of a time sequence of 50 images (separated by 0.5 sec) it is possible to measure the intermittent character of the powder flow. The resulting measure is a cohesive index of the powder. The results obtained from physical testing were systematically plotted as a function of various statistical indices of the shape and size distributions in order to reveal correlations between particle shape properties and physical behaviour. Some clear trends appeared, demonstrating the influence of particle shape on powder physical properties. [less ▲]

The Barabasi-Albert (BA) model with ﬁnite-precision preferential attachment is used to build a wide range of network structures. Spreading epidemics and collective dynamics are investigated on such ... [more ▼]

The Barabasi-Albert (BA) model with ﬁnite-precision preferential attachment is used to build a wide range of network structures. Spreading epidemics and collective dynamics are investigated on such complex networks. Numerical simulations reveal a transition from an exponential scaling to a power law distribution of link numbers per node along with the increase of the tuning parameter ω. The collective synchronization induced by Susceptible- Infected-Recovered-Susceptible (SIRS) epidemiological process is shown to depend on the topological structure of the network. [less ▲]

A vessel is plunged upside down into a pool of 50 cSt silicone oil. An air bell is then created. This bell is vertically shaken at 60 Hz that leads to the oscillation of the air/oil interface. The edges ... [more ▼]

A vessel is plunged upside down into a pool of 50 cSt silicone oil. An air bell is then created. This bell is vertically shaken at 60 Hz that leads to the oscillation of the air/oil interface. The edges of the immersed vessel generate surface waves that propagate towards the center of the bell. When the amplitude of the oscillation increases, wave amplitude increases. We study the influence of the angle between successive sides on the wave patterns. Two kinds of vessel have been studied: a triangular and a square prism. The shape of the air/oil meniscus depends on the angle between the sides of the considered prism. As the amplitude of the oscillation is increased, the triple line, which is the contact line between the solid and the air/oil interface, moves up and down. Above a given acceleration that depends on the immersion depth and on the shape vessel, wave goes under the corner edge of the bell. During the oscillation, the wave generates at the edges presents a singularity that leads eventually to a jet and a drop ejection. A drop is ejected at each oscillation. More complicated ejection can be produced with further increase of the amplitude. This is a sample arXiv article illustrating the use of fluid dynamics videos. [less ▲]

We have studied the splashing dynamics of water drops impacting granular layers. Depending on the drop kinetic energy, various shapes are observed for the resulting craters. Experimental parameters that ... [more ▼]

We have studied the splashing dynamics of water drops impacting granular layers. Depending on the drop kinetic energy, various shapes are observed for the resulting craters. Experimental parameters that have been considered are : the size of the millimetric droplets ; the height of the free fall, ranging from 1.5 cm to 100 cm ; and, the diam- eter of the grain. As the drop is impacting the sand layer, energy is dissipated and a splash of sand occurs. Meanwhile, surface tension, in- ertia and viscosity compete, leading to strong deformations of the drop which depend on the experimental conditions. Just after the drop en- ters into contact with the sand, imbibition takes place and increases the apparent viscosity of the fluid. The drop motion is stopped by this phenomenon. Images and fast-video recordings of the impact allowed to find scaling laws for the crater morphology and size. <br />This abstract is related to a fluid dynamics video for the APS DFD gallery of fluid motion 2010. [less ▲]

The invention relates to a method for separating a first amount of liquid into a plurality of second amounts of liquid, the method comprising the steps of bringing the first amount of liquid (210) into ... [more ▼]

The invention relates to a method for separating a first amount of liquid into a plurality of second amounts of liquid, the method comprising the steps of bringing the first amount of liquid (210) into contact with at least one first fibre (110) being arranged substantially vertical, allowing the first amount of liquid to drain of the first fibre, thereby forming a coating film on the fibre, allowing the coating film to decompose, thereby forming a plurality of second amounts of liquid (220), and allowing the second amounts of liquid to drain of the first fibre and being captured at a crossing point (130) being constituted by the first fibre and at least one second fibre (120) being arranged substantially perpendicular to the first fibre and touching the first fibre. Furthermore, the invention relates to an apparatus for separating a first amount of liquid into a plurality of second amounts of liquid. [less ▲]

The extremely slow compaction dynamics of wet granular assemblies is studied experimentally. The cohesion, due to capillary bridges between neighboring grains, is tuned using different liquids having ... [more ▼]

The extremely slow compaction dynamics of wet granular assemblies is studied experimentally. The cohesion, due to capillary bridges between neighboring grains, is tuned using different liquids having speciﬁc surface tension values. The compaction dynamics of a cohesive packing obeys an inverse logarithmic law, like most dry random packings. However, the characteristic relaxation time 􏰌 grows strongly with cohesion. A model, based on free volume kinetic equations and the presence of a capillary energy barrier, is able to reproduce quantitatively the experimental curves. [less ▲]

The swimming movements of C. gariepinus larvae were recorded with a high-speed camera (400, 500 and 800 fps) from 0 to 336 hours post-hatching. Movements of adult fish were also recorded to provide ... [more ▼]

The swimming movements of C. gariepinus larvae were recorded with a high-speed camera (400, 500 and 800 fps) from 0 to 336 hours post-hatching. Movements of adult fish were also recorded to provide information on the last developmental stage. Seven landmarks positioned on the fish midline were used during tail beating to determine various parameters during ontogeny and, on the basis of these parameters, to describe the first appearance of swimming movements and their development and efficiency during growth. Larvae were unable to swim at hatching (4 mm total length). Swimming movements were established at 48 hours posthatching when the fish measured between 7 and 8 mm total length and the yolk sac was more than 95% absorbed. At this stage, lateral excursion of the head appeared strongly reduced (from 13% to 6% of the total length). The efficiency of swimming movements increased throughout ontogeny, as did the homogeneity of the speed of the propulsive wave. Spontaneous swimming speed of 1 to 10 TLs-1 were observed in early stage (8-12 hPH). The various speed induced significant variations in parameters such as the amplitude of lateral head movements, swimming efficiency, and body rigidity. No major change was observed at the theoretical flow-regime transition. [less ▲]